refactor: remove underline animation and update styling

- Remove underline-animation UnoCSS shortcut from uno.config.ts
- Update Navbar component to remove underline-animation classes
- Remove inline script for link transition animations
- Add cover images to existing posts
- Update font and date display classes in index pages
- Modify global CSS for iOS rendering optimization

src/components/Scrollbar.astro

@@ -7,11 +7,11 @@ function initScrollbar() {
   const bodyElement = document.body
   if (!bodyElement.hasAttribute('data-scrollbar-initialized')) {
     scrollbarsInstance = OverlayScrollbars({
-			target: bodyElement,
-			cancel: {
-				nativeScrollbarsOverlaid: true,  // don't initialize the overlay scrollbar if there is a native one
-			}
-		}, {
+      target: bodyElement,
+      cancel: {
+        nativeScrollbarsOverlaid: true,
+      },
+    }, {
       scrollbars: {
         theme: document.documentElement.classList.contains('dark') ? 'scrollbar-dark' : 'scrollbar-light',
         autoHide: 'scroll',